1. Field of the Invention
The invention relates to an adjustable orthodontic bracket assembly, adapted for use with an arch wire, wherein different sizes of arch wire may be utilized and vector forces acting upon a tooth may be changed or varied, all without removing the bracket assembly from the tooth being treated.
2. Description of the Prior Art
In orthodontic practice, arch wire bending is a time consuming, but essential component of the treatment procedure. Tooth alignment problems are corrected by applying appropriate bends to a generally U-shaped arch wire. When out-of-line, or malposed, teeth are secured to the arch wire by means of orthodontic brackets, forces exerted upon the teeth to move them into a desired orientation over a period of time to correct malocclusions of the teeth. Teeth initially having proper alignment are secured to unbent portions of the arch wire and may serve to define an "ideal" orientation to which the other teeth are directed.
The modes of tooth movement required for correcting malocclusions of the teeth include: up-down (elevating or lowering a tooth within its socket); rotation (turning of the tooth in its socket about its longitudinal axis either clockwise or counter clockwise); tipping (tilting of the tooth toward the front, or mesially of the dental arch; or toward the back, or distally of the dental arch); and torquing (twisting, or turning, the tooth about an axis formed by the arch wire, either toward the tongue, or lingual surface of the mouth, or toward the cheek or lip, or buccal or labial surface of the mouth).
Present day orthodontic brackets are applied to the teeth by bonding the bracket directly to the teeth. Each bracket is typically provided with a slot for arch wire containment, or an arch wire receiving channel, and ligature tie grooves, or wings, to receive elastic rings, or rubber bands, or tie wires for securing the arch wire to each bracket. In older techniques, the brackets were first welded to metal bands and the metal bands were then slipped over the teeth and cemented into place. Present one-piece orthodontic brackets are cast or molded to have a fixed, predetermined amount of torque, tipping, and sometimes rotation designed into the particular bracket. These brackets are designed to limit arch wire bending somewhat for average, normally-shaped teeth, and it is assumed that the bracket will be placed and bonded in a precisely determined position upon the tooth. Since provision has only be made for "average" teeth in these fixed, one-piece bracket systems, there is typically no allowance for normally-occurring differences in tooth anatomy, or in bracket placement errors. Bending of the arch wire is therefore typically required to correct the alignment problems. In many treatments, it may be necessary to remove the brackets from the teeth, and rebond them in a different position; however, this can be a time consuming process.
It has been proposed to provide multi-piece bracket systems, which typically include a bracket and a bracket holder mounted upon the tooth, as an attempt to eliminate some arch wire bending procedures, as well as an attempt to avoid removal and rebonding of the bracket. A disadvantage of such systems has been a large initial expense because the orthodontist is required to purchase and maintain an inventory of a very large number of specially slotted brackets. Furthermore, identification of the proper bracket for each tooth and each situation is believed to be quite time consuming. It is believed that such systems also suffer from the disadvantage that it is typically necessary to remove the bracket from its holder in a mesial-distal (side-to-side) movement, a difficult operation particularly with small, closely positioned teeth. Some of these systems also required that the orthodontist insert small pin members in order to hold the multi-piece bracket systems together into their desired configuration, which can also be a difficult and time consuming task.
A major disadvantage associated with both prior art one-piece or multi-piece bracket assemblies has been that once the orthodontist begins the orthodontic treatment and selects a particular size arch wire to use, he must continue to use that particular arch wire throughout the treatment procedure. If he decides to change the size of the arch wire, it is necessary, in the case of one-piece brackets, to remove all of the brackets from the teeth, and replace them with different brackets having a larger arch wire slot, or arch wire receiving channel, in order to accommodate the larger, or smaller, size arch wire. In this regard, typically more force can be applied to the teeth when a larger arch wire is used. In the case of multi-piece bracket assemblies, it would be necessary to remove all of the brackets from the holders in order to substitute different brackets having either a larger or a smaller size slot, or arch wire receiving channel. Furthermore, in many of the single-piece brackets, and multi-piece bracket assemblies, repeated adjustments to the arch wire, and/or repeated substitution of bracket pieces is required as the treatment progresses and the malposed teeth move into their desired orientation.
An additional disadvantage associated with prior art orthodontic brackets relates to the configuration of the slot, or arch wire receiving channel. They are all typically formed as a generally U-shaped channel, having the vertically extending legs joined to the base at right angles to one another, and there are also right angles formed at the exit ends of the channel. Thus, movement of the arch wire, whether caused by sliding movement of the arch wire within the channel, or caused by bending of the arch wire by the orthodontist, can cause the arch wire to bind within the slot of the bracket at the sharp edges formed by the right angles.
Accordingly, prior to the development of the present invention, there has been no adjustable orthodontic bracket assembly adapted for use with an arch wire which: is simple and economical to use; permits different sizes of arch wires to be utilized without either removing and rebonding the bracket to the teeth or by changing all the bracket components of multi-part systems; easily permits changing the vector forces acting upon the teeth without removing the bracket or substituting an extensive number of bracket components; and prevents binding of the arch wire within the arch wire receiving channel, or slot. Therefore, the art has sought an adjustable orthodontic bracket assembly, adapted for use with an arch wire, which: is simple and economic to use; permits different sizes of arch wires to be utilized in the orthodontic treatment, without removal and rebonding of different sized brackets to the teeth, or without substituting an entirely different size set of bracket members; permits the vector forces exerted upon the teeth to be easily changed without removing and rebonding brackets to the teeth, or without substituting an excessive number of bracket components; and prevents binding of the arch wire within the arch wire receiving channel.